Lighting has many applications across a number of industries. Different spectrums of light serve different purposes that range from illuminating a work environment for optimizing safety to being used in the manufacturing of printing circuit boards. One application in particular that is experiencing a rise in attention is horticulture. Artificial lighting has been used to grow plants for decades, but the technology to do so has experienced only minor improvements compared to innovations in all other aspects of growing plants, such as grow mediums, nutrients, and irrigation systems. The use of lighting for horticulture is expected to increase dramatically over the coming decades, which will give rise to more advanced technologies and control methods that eliminate the deficiencies of the known lighting systems.
Conventional lighting control systems are limited by the lighting technology used within the system. Typical lighting used in horticultural applications, such as high intensity discharge (HID), produce a fixed spectrum inherent to the bulb being used. Two different bulbs are commonly used; Metal halide (MH) bulbs produce blue-focused light (400-500 nm), which is most useful during vegetative growth stages, whereas high pressure sodium (HPS) bulbs produce red-focused light (600-700 nm), which is better suited for flowering growth stages. Light emitting diode (LED) technology is limited in terms of the diodes used to create the lighting array within a fixture. The spectrum produced is a conglomerate of the diodes used in the array; however, the result is an incomplete spectrum due to wavelengths being omitted, since such a conglomerate may not have a diode for every wavelength.
Modification of the spectrum produced is based on the active diodes. For example, if a user desires a red-focused spectrum, the 400 nm to 500 nm diodes would be deactivated, resulting in loss of a full spectrum and light intensity. Light intensity is described herein in terms of photosynthetic photon flux density (PPFD) measured in micromoles of photons per meter squared per second, (μmol/m2/s). This sacrifice is not desirable as all plants have evolved under a full spectrum of considerable intensity, so there is a need to be able to control spectrum without omitting parts of it entirely. While an LED can be dimmed, such dimming only decreases intensity and does not affect the spectrum produced.
As a result of these limitations of the present technology, a user's ability to more effectively achieve the ultimate goal of an artificial light source, namely the replication of natural sunlight, is reduced. These limitations include spectral shifts over the course of a day based on the sun position, angle of incidence, and other attributes. Specifically, the spectrum of natural sunlight tends toward a more red focus during sunrise and sunset and a more blue focus in the afternoons. Further, there is a progression of the spectrum of the sunlight between sunrise and sunset that is not easily replicated.
Beyond spectral control, conventional technologies lack the ability to integrate well with auxiliary components that are used for monitoring and control of an indoor horticulture environment. Currently, expensive add-on control systems are used to manage these lighting technologies, yet still fall short in capabilities and overall integration of all parts of the system. Integrating other functions into this basic configuration is not only expensive, but typically requires professional installation and configuration.
Even with the use of available add-ons, some functions are not available, such as automatic height adjustment of a luminaire or using a luminaire to visually monitor the crop area that a light is covering. Optimum distance from canopy is approximately twelve to eighteen inches, and as of now no lighting fixture can be automatically adjusted to maintain this optimum height throughout the growth cycle.
Other features not available using conventional lighting technologies include the ability to determine root mass using non-invasive sensors as well as to track height adjustment data to analyze plant growth rates. For example, current control systems could not detect the size or track the growth rate of the root mass and adjust the feeding schedule automatically based on the data.
Accordingly, there is an unmet need for a horticultural lighting system where there is control over power (e.g., intensity), spectrum (e.g., wavelength), coverage (e.g., area), and other factors, as a function of time. Because plants go through different growth stages, where each stage benefits from a different light configuration, tailoring a horticultural lighting system to these different stages would result in a highly efficient and optimized system. However, present technology does not perform this dynamic configuration to optimize for different growth stages because present technology does not have the ability to monitor and adjust spectrum, power, heat dispersion, moisture, and other variables conducive to growing. Accordingly, there is a need to have horticultural lighting that can respond dynamically to environment conditions using various sensors and other horticultural components.
Accordingly, there is a need for a lighting technology that allows the successful integration of auxiliary functions as well as an increased ability to replicate natural sunlight more accurately based on the spectral changes over the course of a day. There is also a need to monitor crops based on the luminaire covering the specific site to increase user control and gain real time plant development data.